During surgery, surgeons need to move (retract) tissues to facilitate access and/or other surgical tasks. Retraction is a critical aspect of all forms of surgery, but particularly minimal access surgery (MAS), where the operating space is limited and the instruments are fed through the abdominal wall via special ports. Normally one of the access ports is dedicated to a retraction instrument and, in normal procedures, an assistant surgeon is required to hold the retraction instrument. While MAS is undoubtedly less traumatic than open surgery, it remains desirable to use as few access wounds as possible.
The demand for a new retraction system is most apparent in the rapidly developing fields of single port laparoscopic surgery (SPLS) and natural orifice surgery. Here, the use of a single small access wound severely limits the number of instruments that can be effectively inserted. In order to ensure optimal utilisation of space within the restricted space offered by the single access port, it is desirable that retraction for these types of surgery should be effected without using the port.
It is known that surgeons have retracted tissue in the above context by suturing between the tissue and the abdominal wall. This is achieved by taking a suture and thread into the abdominal space either via a port or by penetrating the abdominal wall with the suture needle.
Retracting organs using chord-like elements is known. For example, the retraction of hollow organs (arteries, veins, oesophagus) with elastomeric slings is routine in many operations. Similarly, hitching the fundus of the gall bladder to the abdominal wall by percutaneous sutures, introduced many years ago by A Cuschieri, has been used, but for full exposure of the gallbladder for SPLS-cholecystectomy two tethering percutaneous sutures (occasionally three) are needed, at right angles to each other: one to lift the gallbladder and liver anteriorly, and the other to stretch the cystohepatic triangle to the right, thus providing the necessary exposure for safe dissection of the cystic artery and cystic duct, both of which require clipping and division for detachment of the gallbladder from the biliary tract. The precise insertion of these sutures is technically demanding and time consuming. However, their use in SPLS-cholecystectomy serves to confirm that tethering techniques provide effective retraction and surgical exposure of the operative field.
The applicants have identified several problems with using conventional internal or percutanous sutures for laparoscopic exposure of organs: passage of atraumatic sutures (on straight needles) through the abdominal wall can be difficult; the needle has to be reversed, after passage through the gallbladder, in the peritoneal cavity and tied to, or inserted through, the abdominal wall from inside out (in the case of external suture tethers) and the mechanical loads on the tissues from the suture tension are high, resulting in tearing and leakage of, for example, bile. Moreover, the technique is laborious and time consuming especially as usually two and sometimes three suture tethers are needed. Once in place, the direction of pull of suture tethers cannot be changed.